VideoBackup - restore in Winuae ?

[wlcina]

Hello, is there any chance I can return data from my VHS tapes - Videobackuped 10-15 years ago back to Winuae ?

For example grab the video to AVI or MPEG and then use in winuae ?

Can be videobackup HW emulated in winuae (or is it already?) so for example I start videobackup software, put MPEG as input and it will load data ?

[Jope]

Time to rewrite VBS for modern OSes and skip the WinUAE part. :-)

[Amiga1992]

Also, MPEG is a lossy codec, I wouldn't use that, it will probably yield data corruption. You need a lossless codec.

[TCD]

Storing digital data as a backup on a VHS tape deserves a Darwin award to begin with, but after 10+ years... I honestly wish you all the best that you can restore anything

[davideo]

@TCD

If it's been stored in the correct conditions it may be ok.

If not - as you said "Good luck"

Dave G

[TCD]

I can't think of a more 'instable' medium for storing data than VHS or audio tapes, but if there is an easy way to implement it in WinUAE and the tape can be recorded in a way to enable reading the data, I'm the last person to be against that feature Just... the person that offered this method in the first place 'because you can'... deserves the Darwin award for 'awesome ways to store your backups'

[davideo]

Originally Posted by TheCyberDruid

... deserves the Darwin award for 'awesome ways to store your backups'

Dave G

[modrobert]

After reading up a bit on VBS, as Jope mentioned. I think the backups should stand the test of time just fine, much better than most modern software used for backing up files.

Technical background

VBS stores the data on video tape using a black and white video signal. Each scanline contains a number of data bits, which are represented as short horizontal lines.

To deal with potential data losses because of noise or drop-outs on the video tape, the product relies on a highly sophisticated software implementation of the Reed-Solomon error-correcting code. In order to ensure that even a 14MHz Motorola 68020 CPU could handle the data flow to and from the VCR in real time, I implemented the encoder and decoder in highly optimized assembly language. This application of coding theory is the topic of the article Reed-Solomon Error Correction - A fast software implementation, which I wrote for Dr. Dobb's Journal. It appeared in the January 1997 issue.

This is similar to the system used by PAR/PAR2 and RAID 5 to store additional data which can be used for repair. Actually way ahead of its time, would be nice if backup software today could handle crappy backup media this well.

[Toni Wilen]

VBS uses very high serial bit rate (~600 000 bps+) and 9-bit serial mode (1 start bit, 9 data bits, 1 stop bit) which is incompatible with standard PC serial ports.

Someone would need to write VBS "simulator" that reads captured video directly.

[BippyM]

Just capture the video when played on a VHS to a lossless format!

Am I missing something?

[demolition]

Originally Posted by TheCyberDruid

I can't think of a more 'instable' medium for storing data than VHS or audio tapes

All my C64 tapes, both originals and copies, read just fine today, but a majority of my Amiga floppies have died, despite the fact that my C64 tapes are older than my Amiga floppies.
VHS combined with proper error correction should be quite recoverable today, once you get the head tracking properly aligned with the backup tape.

IMO, VHS backup was a good solution back then as it offered high speed backup and lots of space for a low price since most people already had the player. It might not have been perfect, but it was preferable to floppy backups which would have been the alternative.

[TCD]

Originally Posted by demolition

IMO, VHS backup was a good solution back then as it offered high speed backup and lots of space for a low price since most people already had the player.

Reading modrobert's post, doing a bit of looking up how much data capacity a VHS can hold and your argument I've changed my mind too It's mainly about how you store the data on the VHS and the error-correction indeed makes a huge difference regarding standard home recorders and tapes.

[demolition]

You can get reliable data storage from any medium, no matter how unreliable it really is. It is simply a matter of trading storage space for reliability. A CD is also a good example as the raw data is about 3x as big as the data you can put on a data CD, due to the massive amounts of error correction it uses.

[modrobert]

Originally Posted by TheCyberDruid

Reading modrobert's post, doing a bit of looking up how much data capacity a VHS can hold and your argument I've changed my mind too It's mainly about how you store the data on the VHS and the error-correction indeed makes a huge difference regarding standard home recorders and tapes.

You were right about the media being "instable", that was my first thought as well. The big surprise here IMO, considering the age of the software, was the elegant solution to handle error correction.

Originally Posted by bippym

Just capture the video when played on a VHS to a lossless format!

Am I missing something?

That should work, good idea. Just need to code something to handle the lossless format chosen.

[TCD]

Originally Posted by demolition

It is simply a matter of trading storage space for reliability.

Indeed. I had to get an idea about how to store a bit on that very medium so that it will be reliable enough. Would be interesting to have a figure about the raw/usable capacity ratio of a VHS.

[modrobert]

FYI: I sent an email to Hugo Lyppens, the author of VBS (Video Backup System Amiga), asking for the source code.

[demolition]

Originally Posted by TheCyberDruid

Indeed. I had to get an idea about how to store a bit on that very medium so that it will be reliable enough. Would be interesting to have a figure about the raw/usable capacity ratio of a VHS.

According to wiki, the luma resolution is about 335x576 at 25Hz in PAL. This is 4.8Mbps if only two levels are used. For a 4h tape, I get that to 70GB raw storage space. How much could actually be stored reliably? Obviously much less, but I'm thinking it should be in the GB range.

[TCD]

I'd also assume the ratio would be around the 1/100 mark. Thanks for that figure Maybe someone can tell that used the software how much space was available?

[modrobert]

I haven't tried VBS, but this was on the same page I found the other info.

Speed and Capacity

There are special backup modes for Amigas with an 68020 or higher CPU (A1200, A2500, A3000, A4000). The first one gives a speed improvement of a factor 2 compared to V1.5, without data compression. The typical thoughput in this case is 85MB per hour, for a total of 340MB per 4-hour video tape! The 68020-compressed mode adds data compression to this, and is up to 3 times as fast as V1.5 (depending on the compression ratio achieved). With 130MB per hour, 520MB will fit on a 4-hour tape! On an 68000 Amiga, the throughput is about 40MB per hour.

Source: http://www.hugolyppens.com/VBS.html

[jimbob]

I seem to remember one of my Amiga buddies of yore using this. I was curious why TCD thought this worthy of a Darwin award. Seems like a great way to not spend loads of money on proper SCSI tape drive or whatever real back up system. VHS tape may be a crappy medium for analogue video but as has been said, a decent encoding method for digital data and this type of tape should be totally servicable. Could this type of tape even be better in terms of noise immunity and decay because being designed for analogue signals it would need a high dynamic range?

I'm trying to imagine how it worked though. Did the software actually generate a video signal recorded to VHS via composite or even RF? If so I'm having more trouble imagining how you recovered the data. I can't imagine you did it with a frame grabber

As for getting it back now, I think you might need a quality video capture card since you need the raw frames. Any compression would destroy the data which probably rules out any cheapy USB capture devices.